It wasn't that long ago that
It wasn't that long ago that everyone thought ethanol was a pipe dream; and now it's being commercialized and sold at the pump.
According to the Origin Oil website, there is no target date. The first entry, though, will be to blend algae with other, much cheaper ingredients such as municipal and forestry waste. According to them, the algae provides an energy boost and its petrochemical profile.
From all that I can uncover now, that blend is what's targeted first to become an affordable alternative to petroleum; I assume as a first wave. After that, gasoline is a blend, too. So, the pure play on algae oil will likely increase over time. How much time? Honestly, I do not know. I do know the technology is there; and like other technologies and processes, it takes time to ramp up and increase commercialization.
Recall that everyone thought ethanol blends from corn would indeed be the savior; and it was far from becoming reality. There was lots of talk, then investment, then finally action. And now it is in the system, but algae fuel has a distinct advantage in that it bypasses a key element in our food supply. So I can see algae fuel replacing ethanol first.
Can algae fuel fall by the wayside? Sure, because commercialization requires large investments. But investments from the likes of Exxon tell me even they know it is in their best interest. Why drill for a finite quantity which is captial intensive, when they have the potential to grow, extract and replenish it?
By the way, your time question also applies to the newer IC engine technologies on the horizon, like the split cycle of Scuderi and Tour, the HCCI of GM and the closed-loop external combustion steam engine of Cyclone Power.